Tuesday, May 21, 2013

New paper finds sea level rise has greatly decelerated over past 10,000 years

A paper published today in the Journal of Quaternary Science reconstructs sea level rise in New Jersey, USA over the past 10,000 years and "concludes that relative sea levels rose at an average rate of 4 mm per year from 10,000-6,000 years ago, 2 mm per year from 6,000 to 2,000 years ago, and 1.3 mm per year from 2,000 years ago to AD 1900." Thus, the paper finds a large deceleration in sea level rise over the past 10,000 years, to a rate in 1900 essentially the same as during the past seven years. According to the 2012 NOAA Sea Level Budget, global sea levels rose at only 1.1 - 1.3 mm/year from 2005-2012, which is less than half of the rate claimed by the IPCC [3.1 mm/yr] and is equivalent to less than 5 inches per century. Contrary to alarmist claims, sea level rise decelerated over the 20th century, has also decelerated since 2005, and there is no evidence of any human influence on sea levels.

BENJAMIN P. HORTON et alABSTRACT: We investigated the effect of tidal-range change and sediment compaction on reconstructions of Holocene relative sea level (RSL) in New Jersey, USA. We updated a published sea-level database to generate 50 sea-level index points and ten limiting dates that define continuously rising RSL in New Jersey during the Holocene. There is scatter among the index points, particularly those older than 7 ka. A numerical model estimated that paleotidal range was relatively constant during the mid and late Holocene, but rapidly increased between 9 and 8 ka, leading to an underestimation of RSL by ∼0.5 m. We adjusted the sea-level index points using the paleotidal model prior to assessing the influence of compaction on organic samples with clastic deposits above and below (an intercalated sea-level index point). We found a significant relationship (p = 0.01) with the thickness of the overburden (r = 0.85). We altered the altitude of intercalated index points using this simple stratigraphic relationship, which reduced vertical scatter in sea-level reconstructions. We conclude that RSL rose at an average rate of 4 mm a−1 from 10 ka to 6 ka, 2 mm a−1 from 6 ka to 2 ka, and 1.3 mm a−1 from 2 ka to AD 1900.